Process for producing sulphuric acid



pil 26, 1932. H, KREBS ET AL PROCESS FOR PRODUCNG SULPHURIC AHCID Filed Dec. 14, 1928 ngz.

il Ww Patented Apr. 26, 1932 i UNITED STATES PATENT GFFICE HANS Kanne AND noi-.F Bonennns, or Hnrrcns'rnn'r, GERMANY, AssIeNoRsor ONE- THIRD To MANSFELD AKTIENGESELLSCHAFT EUR BERGBAU UND HUTTENBETRIEB,

OF EISLEBEN, GERMANY PROCESS FOR PRODUCING SULPHURIC ACID Application filed December 14, 1928, Serial No. 6,038, and in Germany January 24, 1928.

Our invention relates to improvements in apparatus for producing sulphuric acid.

In the manufacture of sulphuric acid, processes have recently been developed, which no longer make use of the customary lead chambers, but which carry out the sulphuric acid process in other apparatus and which at the same time aim at obtaining a sulphuric acid of higher concentration than that obtained by the chamber process. All these new processes have, however, like the old ones the disadvantage that the apparatus for carrying them out is constructed of lead, which possesses insufficient mechanical strength and chemical resistance. The low mechanical strength of the lead has the disadvantage, that difticult and expensive auxiliary constructions are necessary to impart the necessary Strength and durability to the lead structures. To this must he added, that in the intense process it is impossible to avoid great temperature uctuations and mechanical actions on the lead by vibrations or iinpinging acid. This fact results in the lead becoming rapidly fatigued, brittle and fragile. Equally serious are the drawbacks resulting from the insuliicient chemical resistance of the lead against nitrous acids and gases. To obtain an intense action of the process, it is necessary to operate with acids of as high a nitrous content as possible. At certain places of the apparatus very large quantities of nitrous gases are therefore liberated, which have a strong chemical action upon the lead. The formation of the chamber crystals so extremely dangerous for the lead is thus unavoidable.

To this disadvantage of the lead from the mechanical point of view must thus be added the very serious disadvantage in chemical respects.

These drawbacks are edectively eliminated by our present invention. Our invention consists in apparatus for the manufacture of sulphuric acid in the construction of which the use of lead is entirely eliminated and the lead is replaced by a material which has no Such disadvantages. This material is iron. By iron is to be understood iron in its widest sense, such as iron of all the commerical descriptionsfor instance castiron, wroughtiron, mild steel, steel, cast steel and all iron alloys in which iron is the main constituent. Another object of our invention is to give the parts of theiron equipment the most economical shape and configuration to adapt them to the new purpose.

It has hitherto not been considered possible to replace the lead by iron, because it was fearedthat iron would be chemically strongly attacked by the gases and acids. Wre have, however, ascertained that the resistance of the iron vagainst the gases and acids of intense processes exceeds that of the lead considerably, provided the process is conducted in the proper way. Under the proper way is to be understood that the carrying out of the formation of the acid is absolutely followed only with such circulating acids land produced acids which, in their raduation, eX- ceed 55 B. The lowering of the acids from this graduation 4must, under all circumstances, be avoided since otherwise the main-` tenance of the apparatus could not be further guaranteed. The use of iron is further possible `also in the old chamber process in Gay- Lussac towers and Glover towers.

The drawings aiiixed hereto and forming part of our specification shows our invention applied to a tower as used in the manufacture of sulphuric acid.

In the drawings Fig. l shows an acid tower constructed of lead, for instance according to Petersens system, in sectional plan and sectional elevation, the latter along line zia-a2l of the plan, and

Fig. 2, an acid tower according to our invention constructed of iron shows likewise in sectional plan and sectional elevation, the latter along line y-y, in order to show clearly thetechnical and economical progress attained by the replacementV of lead by iron.

vReferring to Fig. 1, it will be seen that it is necessaryto protect the shell a constructed of lead of the hitherto used towers `by a complete lining` of acid-resisting bricks Z2 before the filling proper c of the tower can be introduced. ,In towers of small diameter the lining of bricks must be so thick, that the internal pressure can be taken up by the to our invention.

bricks. In towers of v comparatively large diameter the pressure exerted upon the lead shell by the iilling through the bricks may be taken up by an external structure. As this figure clearly shows it is in the latter case necessary to envelop the lead shell completely by an auxiliary structure consisting of longitudinal timber d and wooden segments e, which wooden structure is in its turn reinforced by iron bands f and a lateral supporting structure g. The leaden bottom of the tower must also be protected against the mechanical action of the dripping acid by a layer of acid-proof bricks or stones. furthermore necessary to provide for the granular lling of the tower a grid L of acidproof bricks, which enables a uniform distribution of the gas below the filling '0. The roof of the tower must be suspended from an iron auxiliary construction i and the weight of the roof be carried by special lateral stays.

Far simpler in construction is the tower, if, instead of lead, iron is used according On referring to Fig. 2 of the drawings showing our improved tower it will be seen, that this tower consists of a simple iron container or receptacle, the roof of which supports itself without any auxiliary construction, the bottom of which possesses sucient strength to resist mechanical actions and the side walls of which are capable of taking up the pressure of the lilling materials lo without the use of any auxiliary structure. The very complicated grid or grill of acid-proof bricks'is dispensed with and its place is taken by a perforated iron plate Z, which may rest upon low pillars m of iron or any suitable acid-proof material.

l/Ve have ascertained that the costs of such a tower constructed of iron are about 40 p. c. less than those of one constructed of lead.

Various modifications and changes may be made without departing from the spirit and the scope of the invention, and we desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art.

Ve claim as our invention A process for making sulphuric acid in accordance with the nitric oxid method which comprises bringing the reaction gases and vapors into contact with one another in a container of which the walls contacting with the acids are made mainly of ferrous metal while maintaining the concentrationl of the circulating acids and produced acids above a minimum at which the same is capable of attacking the walls of the container.

In testimony whereof we have affixed our signatures.

HANS KREBS. ROLFBORCHERS. y

It is 

